There are conventionally known transfer robots that transfer thin plate-like workpieces such as semiconductor wafers or liquid crystal panels. In addition, there are also known techniques of installing such a transfer robot in a local clean room (hereinafter, referred to as a “transfer room”) provided between an opening and closing device for opening and closing a storage container for semiconductor wafers and a processing room for the semiconductor wafers. Note that the transfer room is not limited to be installed only between the storage container and the opening and closing device.
The above-mentioned opening and closing device is called, for example, a load port, and opens and closes, in the transfer room, a detachable cover provided on the storage container. A part of the opening and closing device holds the cover and moves down as a unit together with the cover so as to slide downward, thereby opening the cover of the storage container. The cover is opened in the transfer room, so that dust or the like does not adhere to the thin plate-like workpieces or other parts in the storage container. Opening the cover allows the transfer robot to carry in and out the thin plate-like workpieces. Therefore, the transfer room needs to have therein an area (hereinafter, referred to as an “exclusive area”) for the opening and closing device to perform attaching and detaching operations of the cover to and from the body of the storage container. The exclusive area is stipulated in the Semiconductor Equipment and Materials International (SEMI) standard. For that reason, there are proposed techniques for reducing a footprint (area) required by the transfer room while disposing the transfer robot so that the minimum turning area of the transfer robot does not overlap with the exclusive area (refer, for example, to Japanese Patent Application Laid-open No. 2008-28134).
However, when the transfer robot is disposed so that the minimum turning area of the transfer robot does not overlap with the exclusive area, the area of the transfer room as viewed from the top tends to be large, and thus, there has been room for improvement from the viewpoint of downsizing of the transfer room.